1. Field of the Invention
The field of art to which this invention pertains is solid bed adsorptive separation. More specifically, the invention relates to a process for separating a carbohydrate from a mixture of carbohydrates using an adsorbent comprising a crystalline aluminosilicate or cationic exchange resin material and having the capability of selectively adsorbing a component from the feed mixture.
2. Prior Art
It is known in the separation art that certain crystalline aluminosilicates referred to as zeolites can be used in the separation of a component from an aqueous solution of a mixture of different components. For example, adsorbents comprising crystalline aluminosilicate are used in the method described in U.S. Pat. No. 4,014,711 to separate fructose from a mixture of sugars in aqueous solution including fructose and glucose.
It is also known that crystalline aluminosilicates or zeolites are used in adsorption processing in the form of agglomerates having high physical strength and attrition resistance. Methods for forming the crystalline powders into such agglomerates include the addition of an inorganic binder, generally a clay comprising silicon dioxide and aluminum oxide, to the high purity zeolite powder in wet mixture. The blended clay zeolite mixture is extruded into cylindrical type pellets or formed into beads which are subsequently calcined in order to convert the clay to an amorphous binder of considerable mechanical strength. As binders, clays of the kaolin type are generally used.
It is known in the separation art that certain ion (i.e. cation) exchange resins can be used in separating components from a fluid mixture, particularly a saccharide from an aqueous solution of saccharides. Examples of such art are U.S. Pat. Nos. 4,025,357; 4,022,637; 3,928,193; 3,817,787; 3,806,363; 3,692,582; 3,416,961; 3,184,334; 3,174,876; 3,044,906; 3,044,904; and 2,813,810. Common ion exchange resins used in the prior art processes are alkali metal and alkaline earth metal salts of a polystyrene sulfonate cation exchange resin cross-coupled with divinylbenzene.
It is also known that various carbohydrates (e.g. sorbitol, glycerol, xylitol, inositol and allose) interact strongly with and form complexes with the cations of the lanthanide series of metals (see Kieboom, A. P. et al, J. Roy. Neth. Chem. Soc., 96, p. 35, 1977; Kieboom, A. P. et al, Tet. Let. 42, p. 3713, 1974; Angyal, S. J. Tet. 30, p. 1695, 1974; Angyal, S. J., Carbohydrates in Solution, p. 106, American Chemical Soc., Washington, D.C., 1971.)
I have discovered a process for separating a carbohydrate from a mixture of carbohydrates which utilizes an improved adsorbent comprising a crystalline aluminosilicate or cation exchange resin, the exchangeable cationic sites of which are exchanged with cations of a rare earth metal.